Improvement in packings for pistons and stop-va es



P. GIFFAHD. Packing for Piston and Stop-Valves.

. N0. 138,633, `Patented May 61873.

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www/ W' l 4,4 I f UNITED STATES PAUL GIFFARD, OF PARIS, FRANCE, ASSIGNOR TO CHARLES PATENT Or ADOLPH DICK, OF PITTSBURG, PENNSYLVANIA. l

Specification forming part of Letters Patent No. 138.633, dated May 6, 1873; applcat l February 17, 1873.

To all whom it may concern:

Be it known that I, PAUL GIFFARD, of the city of Paris, in the republic of France, have invented certain Improvements in Pistons, of which the following is a specification:

The object of my invention is to improve the piston for which Letters Patent No. 122,825 were granted to me on the 16th day of J anuary, 1872; and this object I attain by making the ring, which forms a prominent feature in the said patent, of hard material at its outer circumference where it bears against the cylinder, and of softer material at its inner circumference, the compressed fluids in the cylinder acting instantaneouslyon the soft material composing the inner part of the ring so as to insure at once a perfectly tight joint between the said ring and the plate against which it temporarily bears, while the harder outer portion of the ring which bears against the cylinder has the elfect of reducing the friction to a minimum.

It will be unnecessary to explain here the operation of the ring during the` reciprocating movement of the piston, as this is fully set forth in my aforesaid patent. The ring may be made of different materials-compressed paper or paste-board, for instance; but I prefer to make it of vulcanized rubber, as I am enabled to regulate or graduate the vulcanization so that the exteriorof the ring may have the desired hardness and the inner portion the requisite softness.

When the ring has to be applied to a singleacting pump, I prefer to make it in the manner shown in Figure 1 of `the accompanying drawing-that is, with two annular beads or ribs, a a, on its upper surface for bearing on the upper side of the pistons groove; or these annular ribs may be made on the piston and project into the groove of the same, the ring being flat, as shown in Fig. 2. In either case the annular beads or ribs will rapid completion of the joint on n i piston.

For double-acting pumps the have annular beads on both sid in Fig. 3 5 or both sides of the g` have beads,the ring being flat. there may be but one bead, eithe Ion one side of the groove, as in Fig. 4, or o lune side of the ring, for a single-acting pum and for a double-acting pump there maybe but one ing should j as shown ove should bead on each side of the pistons rcove, as in Fig. 5, or on each side of the rin My improved piston may be pplied with the best results to all double and ingle acting pumps for hydraulic purposes, air-pumps, exhaust or vacuum l engines, hydraulic presses, syri ges, 85e. may also be applied to stop-val is in a manner substantially as shown in jg. 6, which will be readily understood wit ut explanation. y

I claim as my invention, and a an improvement in the pump-piston for ich Letters Patent were granted to me on l e 16th day of January, 1872- y 1. The within-described pistring, made softer at the inner than at the g uter circumference, and adapted to the gr ve of a piston, all substantially as and fo i thev purpose herein set forth.

2. The combination of a rece ed piston, a packing-ring, and one or more nular bearings, a a, arranged to limit th y play of the ring, substantially as described. y

1n testimonywhereof I have si y ed my name to this specification in the prese l1 `e of two subscribin g witnesses.

PAUL ,IFFARD Witnesses:

CH. F. THIRION, LYMAN EARL.

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